Multiplex Capacity Tables

DAB and DAB+ services use up their data capacity for a variety of reasons.

Transport Layer
Firstly, a limited amount of data is required to provide a framework for the carriage of the various broadcast services transmitted on the multiplex.

Programme Layer
Secondly, a larger amount of data is used to deliver the various station’s programme audio content, which, together with programme related and non-programme related text (as well as still images where broadcast) is encoded for transmission within the DAB multiplex.

Error Protection Layer
Thirdly, each multiplex uses additional data to make the transmission of each broadcast service robust against interference, using what is known as “error protection”. In the UK, three levels of error protection are available for both DAB and DAB+ services. These error protection levels are known as UEP 3, UEP 2 & UEP 1 for DAB services and as EEP 3A, EEP 2A & EEP 1A for DAB+ services. The original international DAB and DAB+ standards also include further (weaker) levels of error protection (UEP 5 & UEP 4 / EEP 5A & EEP 4A respectively), but these are not permitted for use in the United Kingdom. Just as each individual programme service can operate at its own individual bit-rate, each programme service can also operate using its own individual level of error protection.

The trade-off is between programme data rates, error protection levels and the total number of services carried. Higher audio quality services and / or services with higher error protection levels each need a greater total amount of data when compared to lower audio quality services and / or services using a lower level of error protection.

The standard (lowest) level of error protection which must be used is UEP 3 (or EEP 3A for DAB+ services). Instead of using UEP 3 / EEP 3A, individual programme services on a multiplex can make their signals more robust by using either UEP 2 or UEP 1 (EEP 2A or EEP 1A for DAB+ services). However, using increased levels of error protection requires the use of additional amounts of data. In other words, if higher levels of error protection are used less data capacity remains available for other uses. Therefore, as the following table explains, using higher levels of error protection means that, because it has a finite and fixed data capacity, the overall multiplex is then only able to carry a smaller total number of programme services.

Mutliplex Occupancy Examples

Data Rate Used /Protection Level

Capacity Units Used(Per Programme Service)

Maximum Nunber ofServices on Multiplex

192 kbps / UEP 3

140 CU (DAB)

06 = 840 CU (24 spare)

192 kbps / UEP 2

168 CU (DAB)

05 = 840 CU (24 spare)

192 kbps / UEP 1

208 CU (DAB)

04 = 832 CU (32 spare)

160 kbps / UEP 3

116 CU (DAB)

07 = 812 CU (52 spare)

160 kbps / UEP 2

140 CU (DAB)

06 = 840 CU (24 spare)

160 kbps / UEP 1

168 CU (DAB)

05 = 840 CU (24 spare)

128 kbps / UEP 3

096 CU (DAB)

09 = 864 CU (00 spare)

128 kbps / UEP 2

116 CU (DAB)

07 = 812 CU (52 spare)

128 kbps / UEP 1

140 CU (DAB)

06 = 840 CU (24 spare)

112 kbps / UEP 3

084 CU (DAB)

10 = 840 CU (24 spare)

112 kbps / UEP 2

104 CU (DAB)

08 = 832 CU (32 spare)

112 kbps / UEP 1

[Out of specification]

[Out of specification]

096 kbps / UEP 3

070 CU (DAB)

12 = 840 CU (24 spare)

096 kbps / UEP 2

084 CU (DAB)

10 = 840 CU (24 spare)

096 kbps / UEP 1

104 CU (DAB)

08 = 832 CU (32 spare)

080 kbps / UEP 3

058 CU (DAB)

12 = 840 CU (24 spare)

080 kbps / UEP 2

070 CU (DAB)

10 = 840 CU (24 spare)

080 kbps / UEP 1

084 CU (DAB)

08 = 832 CU (32 spare)

064 kbps / UEP 3

048 CU (DAB)

18 = 864 CU (00 spare)

064 kbps / UEP 2

058 CU (DAB)

14 = 812 CU (52 spare)

064 kbps / UEP 1

070 CU (DAB)

12 = 840 CU (24 spare)

056 kbps / EEP 3A

042 CU (DAB+)

20 = 840 CU (24 spare)

056 kbps / EEP 2A

063 CU (DAB+)

13 = 819 CU (44 spare)

056 kbps / EEP 1A

084 CU (DAB+)

10 = 840 CU (24 spare)

048 kbps / EEP 3A

036 CU (DAB+)

24 = 864 CU (00 spare)

048 kbps / EEP 2A

054 CU (DAB+)

16 = 864 CU (00 spare)

048 kbps / EEP 1A

072 CU (DAB+)

12 = 864 CU (00 spare)

032 kbps / EEP 3A

024 CU (DAB+)

36 = 864 CU (00 spare)

032 kbps / EEP 2A

036 CU (DAB+)

24 = 864 CU (00 spare)

032 kbps / EEP 1A

048 CU (DAB+)

18 = 864 CU (00 spare)

024 kbps / EEP 3A

018 CU (DAB+)

48 = 864 CU (00 spare)

024 kbps / EEP 2A

027 CU (DAB+)

32 = 864 CU (00 spare)

024 kbps / EEP 1A

036 CU (DAB+)

24 = 864 CU (00 spare)

Note:Each line of the above table assumes that all the services listed in column 3 are operated at the same bit-rate and error-correction level as that detailed in column 1.

DAB & DAB+ Service Comparison Table

Programme Service Type (examples)

DAB

DAB+

Notes

Stereo Audio(“high” quality / music services)

192 kbps(140 CU)

80 kbps(60CU)

UEP3 / EEP3A

Stereo Audio(“good” quality / music services)

128 kbps(96 CU)

64 kbps(48 CU)

UEP3 / EEP3A

Stereo Audio(“standard” quality / music services)

112 kbps(96 CU)

48 kbps(36 CU)

UEP3 / EEP3A

Mono Audio(“good” quality / music services)

96 kbps(70 CU)

48 kbps(36 CU)

UEP3 / EEP3A

Mono Audio(music / speech services)

64 kbps(48 CU)

32 kbps(24 CU)

UEP3 / EEP3A

Public Service Announcements(e.g. weather, travel etc.)

48 kbps(35 CU)

24 kbps(18 CU)

UEP3 / EEP3A

NOTES:
The slight differences in the number of capacity units required for some bitrates using DAB or DAB+ can be accounted for by differences in block size. However, the key point is that the bit rate required for a given perceived degree of audio quality is substantially reduced. According to WorldDMB, the DAB+ standard “allows for up to three times as many services per multiplex” such that “[a] 40 kbps sub-channel with HE-AAC v2 provides a similar audio quality (even slightly better in most cases) as MPEG Audio Layer II at 128 kbps” (WorldDMB: 2012: 1).

The enhanced efficiency of the revised standard is reflected in the capacity requirements of receiver design specifications, for example, as set out by the UK government in its ‘Minimum Specifications For DAB & DAB+ In-Vehicle Digital Radio Receivers & Adaptors‘: A receiver must be able to decode a DAB audio service contained in a sub-channel of a size up to and including 280 Capacity Units (e.g. 256 kbps@UEP1)”. DAB audio services are defined in ETSI EN 300 401.A receiver must be able to decode a DAB+ audio service contained in a sub-channel of a size up to and including 144 Capacity Units (e.g. 96 kbps@EEP1A). DAB+ audio services are defined in ETSI TS 102 563 (DCMS: 2013: 13).

DAB & DAB+ BITRATES IN MORE DETAIL (at UEP 3 / EEP 3A):

Bit Rate

DAB

DAB CU

DAB+

DAB+CU

192 kbps

“High” qualitystereo audio

140

Not used by FDN

144 CU

192 kbps: This is the maximum bitrate used for original DAB standard stereo programme services on the FDN Greater Norwich Multiplex. This bit rate cannot be used at higher protection levels (i.e. UEP 2 or UEP 1) because to do so would “break” the 140 Capacity Unit decoding limit of some older DAB receivers.

184 kbps

Out of specification

n/a

Not used by FDN

138 CU

176 kbps

Out of specification

n/a

Not used by FDN

132 CU

168 kbps

Out of specification

n/a

Not used by FDN

126 CU

160 kbps

“Very good” qualitystereo audio

116 CU

Not used by FDN

120 CU

160 kbps: This bitrate is used for original DAB standard stereo programme services on the FDN Greater Norwich Multiplex. Although this bit rate can be used at the higher protection level of UEP 2, it cannot be used at UEP 1, because to do so would “break” the 140 Capacity Unit decoding limit of some older DAB receivers.

152 kbps

Out of specification

n/a

Not used by FDN

114 CU

144 kbps

Out of specification

n/a

Not used by FDN

108 CU

136 kbps

Out of specification

n/a

Not used by FDN

102 CU

128 kbps

“Good” qualitystereo audio<

096 CU

Not used by FDN

096 CU

128 kbps: This is the “typical” bitrate used for original DAB standard stereo programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of UEP 2 and UEP 1.

120 kbps

Out of specification

n/a

Not used by FDN

090 CU

112 kbps

“Adequate” qualitystereo audio

084 CU

Not used by FDN

084 CU

112 kbps: This bitrate may be used for original DAB standard stereo programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of UEP 2 and UEP 1.

104 kbps

Out of specification

n/a

Not used by FDN

078 CU

096 kbps

“High” quality monoaudio services

70 CU

Not used by FDN

072 CU

096 kbps: This bitrate may be used for original DAB standard mono programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of UEP 2 and UEP 1.

088 kbps

Out of specification

n/a

Not used by FDN

066 CU

080 kbps

“Good” qualitymono audio

70 CU

Not used by FDN

060 CU

080 kbps: This bitrate may be used for original DAB standard mono programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of UEP 2 and UEP 1.

072 kbps

Out of specification

n/a

Not used by FDN

054 CU

064 kbps

“Adequate” qualitymono audio

48 CU

“Very high” qualitystereo audio

048 CU

064 kbps: This bitrate may be used for original DAB standard mono programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of UEP 2 and UEP 1.

064 kbps: This bitrate may be used for DAB+ standard stereo programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of EEP 2A and EEP 1A.

056 kbps

Not used by FDN

42 CU

“High” qualitystereo audio

042 CU

056 kbps: This bitrate may be used for DAB+ standard stereo programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of EEP 2A and EEP 1A.

048 kbps

Not used by FDN

35 CU

“Good” qualitystereo audio

036 CU

048 kbps: This is the “typical” bitrate used for DAB+ standard stereo programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of EEP 2A and EEP 1A.

040 kbps

Out of specification

n/a

“Good” qualitymono audio

030 CU

040 kbps: This bitrate may be used for DAB+ standard mono (or stereo) programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of EEP 2A and EEP 1A.

032 kbps

Not used by FDN

24 CU

“Adequate” qualitymono audio

024 CU

032 kbps: This bitrate is used for DAB+ standard mono programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of EEP 2A and EEP 1A.

024 kbps

Out of specificationN

n/a

“communcations” qualitymono audio

018 CU

024 kbps: This bitrate is available for information service (weather, travel etc.) type DAB+ standard mono programme services on the FDN Greater Norwich Multiplex. This bit rate can also be used at the higher protection levels of EEP 2A and EEP 1A.